1. Field of the Disclosure
The present invention relates to a stereoscopic 3D (Three-Dimensional) display device and, more particularly, to a stereoscopic 3D display device allowing viewing of a stereoscopic image by using polarization glasses.
2. Description of the Related Art
A 3D display may be briefly defined as ‘the sum of a system artificially reproducing a 3D screen image’.
Here, the system includes a software technique for displaying an image three-dimensionally and hardware implementing contents created by the software technique as an actual 3D image. The reason of including the software region is because, for 3D display hardware, contents created by a software-wise method are separately required for each stereoscopic implementing method.
Also, a virtual 3D display is literally the sum of a system providing a virtual 3D effect with planar display hardware by using, among various factors providing stereoscopy, binocular disparity, caused by the fact that users' eyes are separated from each other by about 65 mm in a horizontal direction. In other words, when a user looks at an object, the user's eyes see slightly different images (strictly speaking, sharing left and right spatial information) of the object because of the binocular disparity, and when the two images are transferred to the brain of the user via the retina, the brain accurately combines them to allow the user to feel the 3D effect of the image. Based on this, a 2D display device simultaneously displays the two left and right images and sends them to the user's respective eyes to create virtual stereoscopy, which is the so-called virtual 3D display.
In such a virtual 3D display hardware device, in order to display images of two channels on the single screen, in most cases, the channels are outputted by changing lines, namely, one line at a time, in one of horizontal or vertical directions on the single screen. When the images of the two channels are simultaneously outputted on the single display device, due to the hardware structure, in case of an autostereoscopic scheme, the right image is transferred to the right eye and the left image is only transferred to the left eye In case of the method using (wearing) glasses, special glasses suitable to each method is used such that the left eye is covered so that it cannot see the right screen image and the right eye is covered so that it cannot see the left screen image.
Although the channels are outputted by changing lines one by one, because the thickness of the lines and the interval between lines are about 0.1 mm to 0.5 mm, too fine for the user's eyes to recognize, the user's eyes recognize the two images of the respective channels as a single screen. However, compared with the case where 2D screen is used, the amount of information reaching the user's eyes from the screen of the same size is halved per channel, so the resolution and a sensible brightness are reduced to about one half as well.
The stereoscopic image display method includes a method for wearing glasses and an autostereoscopic method in which glasses are not used.
A typical method that does not use glasses (in which the user does not wear glasses) includes a lenticular method and a parallax barrier method.
In the lenticular method, a lenticular lens plate on which cylindrical lenses are vertically arranged is installed in front of a display panel.
In the parallax barrier method, two left and right screens are alternately disposed at certain interval therebetween behind a slit-shaped opening called a parallax barrier, so that the two left and right images can be separately viewed through the opening at a particular point of time. That is, the parallax barrier method simply discriminates the left and right channels by blocking them with a wall, rather than using an optical technique such as a polarization method.
FIG. 1 is a schematic view showing the configuration of a stereoscopic image display device employing parallelax barrier method according to the related art, in which a stereoscopic image and a planar image are selectively switched.
As shown, a stereoscopic image display device 1 includes a backlight light source 40, a display panel 30, and a switching panel 20.
The switching panel 20 includes an opaque slit portion and a transparent slit portion, which have a certain width and are alternately disposed. When an electrical signal is applied to the switching panel, the opaque slit portion becomes opaque and the transparent slit portion becomes transparent.
An observer 10 looks at the display panel 30 via the transparent slit portion of the switching panel 20, and in this case, the observer's left eye (L) sees a left eye region Lp of the display panel 30 via the transparent slit portion of the switching panel 20 and the observer's right eye (R) sees a right eye region Rp of the display panel 30 via the transparent slit portion.
In this manner, the observer's left eye (L) and right eye (R) see different regions of the display panel 30, and at this time, the display panel 30 displays images corresponding to the left and right eyes on the left eye region Lp and the right eye region Rp. Accordingly, the observer can feel a three-dimensional effect according to the binocular disparity (binocular parallax).
However, because the parallax barrier method discriminates images with the structure of simply covering the visual field, not using any particular optical technique, if the observer is not at the position intended initially at the designing, the observer's eyes are not within the corresponding range and the images are seen broken. The restricted positions include left/right positions and front/rear positions.
In addition, in the 2D mode, the barrier degrades the brightness of screen image, and a certain user (observer) may feel that the barrier is unpleasant to his eyes.